.border{
    position:relative;
}

.border:after{
    content:'';
    display:block;
    position:absolute;
    left:0;
    bottom:0;
    right:0;
    height:1px;
    background-color: #ccc;
    transform:scaleY(0.5)
}

@media only screen and(-webkit-device-pixel-ratio: 2){
    .border ::after{
        transform:scaleY(0.5)
}

}



@media only screen and(-webkit-device-pixel-ratio: 3){
    .border::after{
        transform:scaleY(0.3333)
    }
}
